Abstract
The strengthening effect and uniformity of residual stress and strain of 7075-T6 aviation aluminum after laser shock peening were investigated. The finite element simulation model of laser shot peening on 7075-T6 aviation aluminum alloy was established and verified. On this basis and combined with experiment, the microstructure, residual stress distribution and equivalent strain distribution of 7075-T6 aviation aluminum alloy after laser shock peening were studied. An index U for evaluating the strain uniformity in the peened area was proposed based on the statistical processing of the equivalent strain distribution in the peened area. The results show that the average grain size on the peened surface of the specimen was refined to 20–30 μm after LSP, and a residual compressive stress layer with thickness of about 0.5 mm was induced on the surface. Grain refinement and residual compressive stress can promote the strength and fatigue properties of 7075-T6 aviation aluminum alloy. The minimum value of U is obtained in the 6 × 6 spot array (the corresponding overlap ratio is 58%), which suggest that the most uniform deformation peened area can be obtained by using 58% overlap ratio in the laser shot peening process, which can avoid stress concentration and improve fatigue life.
Highlights
Introduction7xxx aluminum alloy has high specific strength, good ductility, and toughness, so it widely used in the manufacture of upper wing skins, stringers, and horizontal/ vertical stabilizers.1,2 7075-T6 aluminum alloy is one of the maximum strength aluminum alloys and is a classic material in the fabrication of wings and cargo panel parts.[3]
The strengthening effect and uniformity of residual stress and strain of 7075-T6 aviation aluminum after laser shock peening were investigated
The results show that, for large area laser shot peening, the residual compressive stress with good uniformity and deep depth can be obtained by using the overlap ratio larger than 50%
Summary
7xxx aluminum alloy has high specific strength, good ductility, and toughness, so it widely used in the manufacture of upper wing skins, stringers, and horizontal/ vertical stabilizers.1,2 7075-T6 aluminum alloy is one of the maximum strength aluminum alloys and is a classic material in the fabrication of wings and cargo panel parts.[3]. Laser shock peening is widely used in surface treatment of aluminum alloy. Hfaiedh et al.[7] established three-dimensional numerical model of laser shock peening and studied the residual stress distribution of 2050-T8 aluminum alloy after laser shock peening. Luo et al.[8] studied the residual stress uniformity of LY2 aluminum alloy after laser shock peening with the overlap ratio of 30%, 50%, 70% and 90%. The results show that, for large area laser shot peening, the residual compressive stress with good uniformity and deep depth can be obtained by using the overlap ratio larger than 50%. The calculation formula of the overlap ratio was given in equation (3)
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